1. Field of the Invention
The invention relates to an electronic apparatus with a remaining-battery-power-indicating function. More particularly, it relates to an electronic apparatus such as portable video camera, cellular phones, portable digital assistants, and the apparatus having a network communication function, which are capable of indicating remaining battery power of a battery pack for supplying electric power to the apparatus.
2. Related Art
A well known portable video camera, which is a typical electronic apparatus, comprises a main body thereof for imaging subject and recording image of the subject and a removable battery pack for supplying electric power to the main body. The main body includes an image pickup device for imaging the subject, a recording unit for recording the information signal of the subject imaged by the image pickup device on a recording medium such as a tape cassette, and a display unit for displaying the image of the subject captured.
Recently, in most cases, the display unit includes a display panel in the form of an LCD panel, for convenience, in addition to an electronic viewfinder (EVF). A user for shooting can look at the subject through such the viewfinder. On the LCD panel, the user, and others as well, can see what is the subject from the image displayed thereon.
Video cameras of this kind often display remaining battery power on their display units to allow the user to show how long the battery pack will be available in the portable use condition of the video cameras. Video cameras disclosed in Japanese Patent Publications H9-297166 and 2000-350371 have two display units consisting of a viewfinder and an LCD panel, respectively. These cameras can detect the use status or use mode of each of the video cameras using a particular display unit (the mode will be referred to as “display mode”). They can also calculate power consumption by or at the present time according to the display modes. They also display an estimated amount of remaining battery time in a single charge based on remaining battery power, namely, remaining battery capacity, on the display unit (the viewfinder or the LCD panel) thereof.
Knowing the estimated amount of remaining battery time for the current display mode, the user can easily grasp how long he or she can continue shooting for this display mode. The user, therefore, can prepare for recharging or replacement of the battery in time, thereby avoiding a malfunction in battery during shooting.
It is noted, however, that the estimated amount of remaining battery time displayed on the respective display units mentioned above merely represents time when the battery is available by battery exhaustion in a current display mode. For example, if only the viewfinder is used now, the estimated amount of remaining battery time shown in the viewfinder indicates estimated available time based on an assumption that the video camera will be subsequently used only in the viewfinder mode. Hence, if the user switches the display mode from the viewfinder to, for example, the LCD panel, the user fails to know how long the battery will be available from now in the LCD mode.
In actuality, various display modes exist in addition to the first display mode using only the viewfinder. For example, there are a second display mode using only the LCD panel, a third display mode using the viewfinder and the LCD panel at a same time, and a fourth display mode using an LCD panel in transferring data via a network if the apparatus has a network communication function, by which an imaged picture is transferred via the network such as the Internet.
Since power consumption rates in these display modes differ greatly, the estimated amount of remaining battery time differs greatly depending on which of the display modes is subsequently used.
In the conventional electronic apparatus, the display unit displays the estimated amount of remaining battery time based on only the current display mode. Consequently, when the display mode is switched from a first to a second display mode, for example, the estimated amount of remaining battery time is re-calculated for the second display mode before it is displayed. This disadvantageously requires certain time for re-calculating the estimated amount of remaining battery time and displaying the estimated amount of remaining battery time thus re-calculated in the second display mode in addition to time for switching the display mode from one to the other. Therefore, it will be very convenient for the user if he or she can access the estimated amounts of remaining battery times for all the possible display modes at once.
Furthermore, in conventional video cameras, the display function for displaying various pieces of information is cut off during charging. Consequently, although a user can see charged condition of the battery, there is no way of directly knowing the estimated amount of remaining battery time in respective display modes during charging. Even if the display unit is modified to display the estimated amount of remaining battery time, it is still impossible then to predict, during charging, whether the shooting will be carried out using only the viewfinder or only the LCD panel. Therefore, displaying the estimated amount of remaining battery time in any of the display modes is suitably determined by a predetermined default display mode.
If the estimated amounts of remaining battery times for all the display modes are known during charging, then it is conceivable that the user may hold sufficient battery capacity for his or her preference in a particular display mode, though the battery is not fully charged. Therefore, he or she can then quit charging of the battery pack without waiting for full charging thereof. This would permit the user to cut down charging time to avoid wasting time in fully charging the battery.
The present invention alleviates the problems as mentioned above. It is an object of the present invention to present an electronic apparatus with a remaining-battery-power-indicating function, namely, display function for displaying the remaining battery power or the estimated amounts of remaining battery times in all the display modes that the apparatus may take simultaneously or selectively.